Method and apparatus for tracking input positions via electric field communication

ABSTRACT

A method and apparatus for tracking input positions via Electric Field Communication (EFC) are provided. The apparatus includes a plurality of receiving electrodes for EFC and a receiver unit. The receiving electrodes detect strengths of input electric fields. The receiver unit compares the strengths of the input electric fields with each other and generates position information regarding the input electric fields.

PRIORITY

This application claims priority under 35 U.S.C. 119(a) to anapplication filed in the Korean Intellectual Property Office on May 19,2009, and assigned Serial No. 10-2009-0043345, the contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a tracking technology, andmore particularly, to a method and apparatus for tracking inputpositions via Electric Field Communication (EFC), where the apparatusprovides a multi-touch function in a non-contact manner.

2. Description of the Related Art

Touch screens are currently being developed that employ EFC technology.The concept of EFC is similar to that of Radio Frequency (RF) mobilecommunication. EFC technology uses human skin as a communication medium,instead of RF. EFC has a data transmission rate of about 2 Megabytes persecond (Mbps) and consumes approximately 5 milliWatts (mW) of power,which provides excellent performance compared with other communicationmethods.

Touch screens display devices that can display a variety of images,letters, etc. They are able to detect a position on the screen orreceive information according to the touch of a user's finger, forexample, so that software can perform a data process based on the touchand then display the processed result. A touch screen includes a touchpanel on which infrared lights are formed in a grid so that it is ableto detect a position when a user's finger or an object touches the gridon the screen. Specifically, when a user's finger touches a letter or animage displayed on the screen of the touch panel, the touch screendetects a position corresponding to the user's touched item so that thesystem can process a corresponding command. Touch screens allow users toeasily acquire required information.

However, conventional touch screens are disadvantageous in that theyneed to detect a user's direct touch, a single position touch, variousand complicated inputs, or the like. Conventional touch screens are alsodisadvantageous because they require additional costs to enhance theresolution. More specifically, it may be impossible to enhance thesensitivity of the touch screen.

SUMMARY OF THE INVENTION

The present invention has been made to address at least the aboveproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the present inventionprovides a method and apparatus for tracking input positions via EFC,where the apparatus provides a multi-touch function in a non-contactmanner.

According to one aspect of the present invention, an apparatus isprovided for tracking input positions via EFC. The apparatus includes aplurality of receiving electrodes for EFC for detecting strengths ofinput electric fields, and a receiver unit for comparing the strengthsof the input electric fields with each other and generating positioninformation regarding the input electric fields.

According to another aspect of the present invention, a method isprovided for tracking input positions via EFC. Strengths of electricfields that are received are measured by receiving electrodes for EFC.The measured strengths of the electric fields are compared with eachother. Position information regarding the input positions is generatedbased on a result of comparing the measured strengths.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will be more apparent from the following detailed descriptionwhen taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating a concept regarding the principle ofEFC;

FIG. 2 is a diagram illustrating an apparatus for tracking inputpositions via EFC, according to an embodiment of the present invention;

FIG. 3 and FIG. 4 are diagrams illustrating embodiments of an apparatusfor tracking input positions via EFC, according to the presentinvention;

FIG. 5 to FIG. 9 are diagrams illustrating examples to which theapparatus for tracking input positions via EFC is applied, according toan embodiment of the present invention;

FIG. 10 is a flow chart illustrating a method for tracking inputpositions via EFC, according to an embodiment of the present invention;and

FIG. 11 and FIG. 12 are diagrams illustrating a connection between areceiving electrode array and a receiver IC, in the apparatus fortracking input positions via EFC, according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Embodiments of the present invention are described in detail withreference to the accompanying drawings. The same or similar referencenumbers are used throughout the drawings to refer to the same or similarparts. Detailed descriptions of constructions or processes known in artmay be omitted to avoid obscuring the subject matter of the presentinvention.

The terms or words described in the present description and the claimsshould not be limited by a general or lexical meaning, and insteadshould be analyzed in accordance with a meaning and a concept throughwhich the inventor defines and describes the present invention to complywith the idea of the present invention.

Referring initially to FIG. 1, a diagram illustrates a concept regardingthe principle of EFC.

EFC relates to a technology that allows for informationtransmission/reception using changes in the electric fields of the humanbody. Specifically, EFC technology implements data communication via thehuman body instead of a cable. Since the human body is conductive, itforms electric fields there around when current flows in the human body.

When a transmitter 101 attached to the user's body is supplied with avoltage, the voltage causes a change in the electric fields on thesurface of the user's body. Simultaneously, this change in the electricfields also causes a change in the strength of a signal received by areceiving electrode 102 near the user's body. EFC technology analyzesthe change in the received signal strength and then detectscorresponding information.

Since EFC uses a 12-16 MegaHertz (MHz) frequency band, instead of an RFband, a received signal strength is determined not by a certain portionof an electric field (a weak electric field or a strong electric field)but by characteristics of an individual's human body (which serves as acapacitor) and a distance between the transmitter 101 and the receivingelectrode 102. Therefore, a transmission/reception level may differaccording to a particular user who will use EFC (or whether acommunication channel is determined through contact between two users oramong a plurality of users) or according to a distance (from the ears tothe leg or from the wrists to the fingers, etc.) along which a user usesEFC.

FIG. 2 is a diagram illustrating an apparatus for tracking inputpositions via EFC, according to an embodiment of the present invention.

Referring to FIG. 2, the apparatus includes an EFC transmitter 201, anEFC receiving electrode array 202, which is shaped as a grid formeasuring the magnitude of input electric fields, a display panel 203, areceiver IC 204, and a display controller 205. In an embodiment of thepresent invention, the receiver IC 204 is an example of a receiver unit.Although the receiver unit is implemented with an IC, it should beunderstood that the present invention is not limited to this embodiment.For example, the receiver unit may be implemented with software orhardware. In the following description, the embodiment will be describedbased on the receiver IC 204.

The EFC transmitter 201 is attached to the human body. The EFCtransmitter 201 supplies a voltage to the human body to form electricfields on the surface of the human body. The EFC receiving electrodearray 202 detects the magnitude of the input electric fields andtransmits information regarding the detected magnitude of the inputelectric fields to the receiver IC 204.

The receiver IC 204 serves as an EFC signal detector that analyzes theinformation regarding the magnitude of the input electric fields anddetects the user's voltage input position. The display panel 203 may beimplemented with an information display device, for example, a LiquidCrystal Display (LCD), a Plasma Display Panel (PDP), a Light EmittingDiode (LED), a presentation display device using a projection screen ora hologram, etc. The display controller 205 controls the display panel203 to display information, such as images transmitted from a system.

In an embodiment of the present invention, the user's voltage inputposition is detected via EFC technology. Since EFC uses a frequency bandcorresponding to a near-field area, its close loop characteristic islarger than the radiation characteristic. Using this characteristic, thevoltage input position can be detected only when the transmitter and thereceiving electrode are close to each other. The EFC receiving electrodearray 202 is located at four edges of the display panel 203 to bemeasured and then the user with the EFC transmitter can place his/herhand at a position on the panel 203 that he/she wants to indicate. Themagnitudes of the input electric fields are measured differently atevery EFC receiving electrode array 202 installed to the four edges.These differently measured values approximately detect the user'sindicated position.

If the user's body approaches a particular position of the EFC receivingelectrode array 202 and electric fields are applied thereto, thereceiver IC 204 analyzes the magnitudes of input electric fields,measured by the electrodes at four locations, and compares them witheach other, thereby detecting the position to which the user's input isapplied. The detected position information regarding the input electricfields can form one frame per preset time period so that it can beconverted into two-dimensional image data. The position where the user'sinput is input and the direction that the user's input is moved can bedetected using the two-dimensional data. If the two-dimensional data isarrayed in grid, a multi-touch can be recognized in a non-contactmethod. The position, movement direction, and movement distance of theinput signal are transmitted to the system, so that they can bedisplayed thereon in a preset manner, or so that they can be linked to aparticular command.

FIG. 3 and FIG. 4 are diagrams illustrating embodiments of an apparatusfor tracking input positions via EFC, according to the presentinvention.

Referring to FIG. 3, a first embodiment of the apparatus includes atransmitter 301, a touch screen module 302, and a system 309. Thetransmitter 301 is attached to the user's body. The transmitter 301supplies voltage to the user's body resulting in electric fields on thesurface of the user's body. The system 309 transmits information to bedisplayed to the touch screen module 302 and executes a preset functionaccording to a signal output from the touch screen module 302.

The touch screen module 302 includes a receiving electrode array 303, adisplay panel 304, bit lines 305, a digitizer 306, a receiver IC 307,and a display controller 308. The receiving electrode array 303 measuresthe magnitude of the input electric fields that are induced on thesurface of the user's body by the transmitter 301, and transmits themeasured magnitude of the input electric fields to the receiver IC 307.The display controller 308 controls the display panel 304 to displayinformation, such as images transmitted from the system 309.

The digitizer 306 is connected to the display panel 304 via the bitlines 305. The digitizer 306 digitizes coordinate information regardingthe display panel 304 and transmits the digital coordinate informationto the receiver IC 307. The receiver IC 307 creates position informationregarding electric fields input to the display panel 304 and movementinformation regarding the position information, using the coordinateinformation regarding the display panel 304 and the informationregarding the magnitude of input electric fields. The receiver IC 307then transmits the position information and the movement information tothe system 309.

Referring to FIG. 4, a second embodiment of the apparatus is implementedin a manner similar to the first embodiment and further includes aproximity sensor 350. The proximity sensor 350 measures how closeapplied electric fields approach the apparatus and outputs its measuredvalue to the receiver IC 307, so that it can also provide a value tocompensate the magnitude of the input electric fields according to adegree of proximity in order to measure the position or the movementdirection of the input electric fields.

In the second embodiment of the apparatus shown in FIG. 4, although theproximity sensor 350 is located at the upper side of the receivingelectrode array 303, the second embodiment may be modified in such a waythat the proximity sensor 350 is located at the lower side of thereceiving electrode array 303, having the same effect as the secondembodiment.

FIG. 5 to FIG. 9 are diagrams illustrating examples to which theapparatus for tracking input positions via EFC is applied, according toan embodiment of the present invention.

FIG. 5 illustrates an LCT TV to which the apparatus for tracking inputpositions via EFC is applied, according to an embodiment of the presentinvention. The LCD TV arrays EFC receiving electrodes 401, 402, 403, and404 at its four corners, respectively. The user has an EFC transmitter405 attached to his/her body. When the user's finger approaches the LCDTV, and does not touch it, the electric fields, induced on the surfaceof the user's body by the EFC transmitter 405, are applied to the EFCreceiving electrodes 401 to 404 via the user's finger. The EFC receivingelectrodes 401 to 404 measure the magnitudes of the input electricfields and detect the position of the user's input. This operation couldalso be applied to select a particular function and execute thefunction.

FIG. 6 illustrates a presentation device using a projection screen or ahologram to which the apparatus for tracking input positions via EFC isapplied, according to an embodiment of the present invention. Thepresentation device arrays EFC receiving electrodes 411, 412, 413, and414 at its four corners, respectively. The user has an EFC transmitter415 attached to his/her body. Like the LCD TV shown in FIG. 5, when theuser approaches the presentation device with a conductive pointingdevice 416 without touching it, the electric fields, induced on thepointing device 416 by the EFC transmitter 415, are applied to the EFCreceiving electrodes 411 to 414. The EFC receiving electrodes 411 to 414measure the magnitude of the input electric fields and detect theposition of the user's input via the pointing device 416. This positioninformation is transmitted to the system to select a particular menu andexecute a corresponding function. The operation could be applied to turnpages of presentation documents.

FIG. 7 and FIG. 8 illustrate portable terminals with display units towhich the apparatus for tracking input positions via EFC is applied,according to an embodiment of the present invention. Each of the displayunits arrays EFC receiving electrodes 421, 422, 423, and 424 at its fourcorners, respectively. The user has an EFC transmitter attached tohis/her body.

Referring to FIG. 7, when the user approaches a particular corner of thedisplay unit with his/her finger, the magnitude of the input electricfields, measured by an EFC receiving electrode located at the particularcorner of the display unit, is greater than those measured by the EFCreceiving electrodes located at the remaining corners of the displayunit. Therefore, the apparatus for tracking input positions can simplydetect the position of the user's input.

Referring to FIG. 8, when the user approaches the display unit of theportable terminal with his/her finger and moves his/her finger in aparticular direction, the apparatus for tracking input positionsmeasures the position of an EFC receiving electrode where the user'sinput occurs, forms position information regarding user's inputs duringthe preset time period with a single frame, and converts it totwo-dimensional image data. The position where the user's input is inputand the direction to which the user's input is moved can be detectedusing the two-dimensional data. The two-dimensional data can also beused to replace screens and menus.

FIG. 9 illustrates a multi-touch input device to which the apparatus fortracking input positions via EFC is applied, according to an embodimentof the present invention. As shown in FIG. 9, the multi-touch inputdevice includes an EFC receiving electrode array 431 formed in grid onthe entire touch screen as well as at the edges of the touch screen. Theuser has an EFC transmitter 432 attached to his/her body. Since themulti-touch input device includes a plurality of EFC receivingelectrodes, arrayed in grid, forming an array, the system for trackinginput positions measures the magnitudes of the plurality of inputelectric fields and creates position information regarding the inputelectric fields, which allows it to support a multi-touch function.

FIG. 10 is a flow chart illustrating a method for tracking inputposition via EFC, according to an embodiment of the present invention.

Referring to FIG. 10, an EFC receiving electrode receives electricfields applied by a user with an EFC transmitter and measures themagnitude of the input electric fields in step 501. For example, if auser approaches an LCD TV or a presentation device, to which theapparatus according to the present invention is applied, with his/herfinger or a pointing device, the EFC receiving electrode measures themagnitude of the input electric fields.

A receiver IC creates position information regarding input electricfields using the information regarding the magnitude of the inputelectric fields measured at each EFC receiving electrode in step 502.Specifically, the EFC receiving electrodes formed in grid measure themagnitudes of input electric fields, compares the magnitudes with eachother, and detect the positions of the input electric fields. Thereceiver IC forms position information regarding input electric fields,created during a present time period, into a single frame in step 503.The receiver IC converts the single frame into image data in step 504.The receiver IC detects movement information and movement distance ofthe input position, using the image data in step 505.

FIG. 11 and FIG. 12 are diagrams illustrating the connection between areceiving electrode array and a receiver IC, in an apparatus fortracking input positions via EFC, according to an embodiment of thepresent invention.

Referring to FIG. 11, when the user's body approaches a particularposition, the apparatus for tracking input positions receives the inputelectric fields via receiving electrode array 601, 602, 603, and 604.The input electric fields are multiplexed to one line by a multiplexer605. The multiplexed signals are amplified by an amplifier 606, so thatthey can be analyzed.

The amplified signals are input to a receiver IC 607. The receiver IC607 analyzes the magnitudes of electric fields measured by four EFCreceiving electrodes, compares them with each other, and then detectsthe positions of the input electric fields.

As shown in FIG. 12, the apparatus for tracking input positions isimplemented to further include a proximity sensor panel 608 in theapparatus shown in FIG. 11. The proximity sensor panel 608 measures howclose input electric fields approach the apparatus for tracking inputpositions. The proximity sensor panel 608 outputs its measured values tothe receiver IC 607, so that it can provide the compensation valuecorresponding to the magnitude of input electric fields according to thedegree of proximity in order to measure the position or movementdirection of the input electric fields.

In the embodiment as shown in FIG. 12, although the proximity sensor 608is located at the upper side of the receiving electrode array(electrodes 601, 602, 603, and 604), this embodiment of the presentinvention may be modified in such a way that the proximity sensor 608 islocated at the lower side of the receiving electrode array (electrodes601, 602, 603, and 604).

As described above, the method and apparatus for tracking inputpositions via EFC, according to the embodiments of the presentinvention, can adjust the spacing between grids by controlling thenon-contact sensitivity, instead of forming a number of grids, therebyenhancing the resolution. Since signal loss in EFC is varied accordingto the characteristics of a medium, i.e., human body, the method andapparatus for tracking input positions, according to the embodiments ofthe present invention, does not need to detect the human bodycharacteristic but can easily perform a compensating operation. If theapparatus for tracking input positions via EFC is associated withdisplay devices, such as a virtual hologram display device or aprojection display device, it can detect a user's input position withouta thin film technology needed to form grids.

While the present invention has been shown and described with referenceto certain embodiments thereof, it will be understood by those skilledin the art that various changes in form and detail may be made thereinwithout departing from the spirit and scope of the invention as definedby the appended claims.

What is claimed is:
 1. An apparatus for detecting an input position using Electric Field Communication (EFC), comprising: a plurality of electrodes configured to measure a strength of input electric fields radiated from an object; and a controller configured to compare the strength of the input electric fields measured at each of the electrode to detect the input position, wherein the input electric fields are generated by a voltage supplied by an EFC transmitter which is connected to the object.
 2. The apparatus of claim 1, wherein the controller is further configured to form information regarding the input position, detected during a preset time period, into one piece of image data, and to determine a movement direction and a movement distance of the input positions, using the preset time period and the image data.
 3. The apparatus of claim 1, wherein the plurality of electrodes are arrayed at each edge of a touch screen.
 4. The apparatus of claim 1, wherein the plurality of electrodes are arrayed, in a grid, in a touch screen excluding edges of the touch screen.
 5. The apparatus of claim 1, further comprising: a sensor panel for measuring a degree of proximity of a system and transmitting the degree of proximity to the controller, wherein the controller compensates a magnitude of the input electric fields according to the degree of proximity output from the sensor panel.
 6. The apparatus of claim 1, wherein the controller comprises a receiver Integrated Circuit (IC).
 7. A method for detecting an input position using Electric Field Communication (EFC), comprising the steps of: measuring a strength of electric fields radiated from an object; and comparing the strength of input electric fields measured at each of the electrode to detect the input position, wherein the input electric fields are generated by a voltage supplied by an EFC transmitter which is attached to the object.
 8. The method of claim 7, further comprising: forming information regarding the input position, generated during a preset time period, into one piece of image data; and determining a movement direction and a movement distance of the input position, using the preset time period and the image data.
 9. The method of claim 7, further comprising: measuring a degree of proximity regarding a system that tracks the input positions using EFC; and compensating a magnitude of the electric fields according to the degree of proximity.
 10. The apparatus of claim 1, wherein the plurality of electrodes are attached to a touch screen and measure the input electric fields in a non-contact manner.
 11. The method of claim 7, wherein the electrodes are attached to a touch screen and detect the input electric fields in a non-contact manner. 